Semiconductor light emitting devices including an optically transmissive  element and methods for packaging the same

ABSTRACT

Methods of packaging a semiconductor light emitting device include dispensing a first quantity of encapsulant material into a cavity including the light emitting device. The first quantity of encapsulant material in the cavity is treated to form a hardened upper surface thereof having a shape. A luminescent conversion element is provided on the upper surface of the treated first quantity of encapsulant material. The luminescent conversion element includes a wavelength conversion material and has a thickness at a middle region of the cavity greater than proximate a sidewall of the cavity.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/398,626 filed Mar. 5, 2009, which is a continuation of U.S. Pat. No.7,517,728 issued Apr. 14, 2009 (U.S. patent application Ser. No.11/055,194 filed Feb. 10, 2005), which claims the benefit of andpriority to U.S. Provisional Patent Application No. 60/558,314, entitled“Reflector Packages and Methods for Forming Packaging of a SemiconductorLight Emitting Device,” filed Mar. 31, 2004, and U.S. Provisional PatentApplication No. 60/637,700, entitled “Semiconductor Light EmittingDevices Including a Luminescent Conversion Element and Methods forPackaging the Same,” filed Dec. 21, 2004, the disclosures of which arehereby incorporated herein by reference as if set forth in theirentirety.

BACKGROUND OF THE INVENTION

This invention relates to semiconductor light emitting devices andfabricating methods therefore, and more particularly to packaging andpackaging methods for semiconductor light emitting devices.

It is known to provide semiconductor light emitting device type lightsources in packages that may provide protection, color selection,focusing and the like for light emitted by the light emitting device.For example, the light emitting device may be a light emitting diode(“LED”). Various problems may be encountered during packaging of a powerLED for use as a light source. Examples of such possible problems willbe described with reference to the cross-sectional illustrations of apower LED in FIGS. 1 and 2. As shown in FIGS. 1 and 2, a power LEDpackage 100 generally includes a substrate member 102 on which a lightemitting device 103 is mounted. The light emitting device 103 may, forexample, include an LED chip/submount assembly 103 b mounted to thesubstrate member 102 and an LED 103 a positioned on the LEDchip/submount assembly 103 b. The substrate member 102 may includetraces or metal leads for connecting the package 100 to externalcircuitry. The substrate 102 may also act as a heatsink to conduct heataway from the LED 103 during operation.

A reflector, such as the reflector cup 104, may be mounted on thesubstrate 102 and surround the light emitting device 103. The reflectorcup 104 illustrated in FIG. 1 includes an angled or sloped lowersidewall 106 for reflecting light generated by the LED 103 upwardly andaway from the LED package 100. The illustrated reflector cup 104 alsoincludes upwardly-extending walls 105 that may act as a channel forholding a lens 120 in the LED package 100 and a horizontal shoulderportion 108.

As illustrated in FIG. 1, after the light emitting device 103 is mountedon the substrate 102, an encapsulant material 112, such as liquidsilicone gel, is dispensed into an interior reflective cavity 115 of thereflector cup 104. The interior reflective cavity 115 illustrated inFIG. 1 has a bottom surface defined by the substrate 102 to provide aclosed cavity capable of retaining a liquid encapsulant material 112therein. As further shown in FIG. 1, when the encapsulant material 112is dispensed into the cavity 115, it may wick up the interior side ofthe sidewall 105 of the reflector cup 104, forming the illustratedconcave meniscus.

As shown in FIG. 2, a lens 120 may then be placed into the reflectivecavity 115 in contact with the encapsulant material 112. When the lens120 is placed in the cavity 115, the liquid encapsulant material 112 maybe displaced and move through the gap 117 between the lens 120 and thesidewall 105. The encapsulant may, thus, be moved out onto the uppersurface of the lens 120 and/or upper surfaces of the sidewall 105 of thereflector cup 104. This movement, which may be referred to assqueeze-out, is generally undesirable for a number of reasons. In thedepicted package arrangement, the lens will sit on a lower shelf if theencapsulant is not cured in a domed meniscus shape prior to the lensattach step. This may cause the lens to not float during thermal cyclingand fail via delamination of encapsulation to other surfaces or viacohesive failure within the delamination, both of which may affect thelight output. The encapsulant material or gel is generally sticky andmay interfere with automated processing tools used to manufacture theparts. Moreover, the gel may interfere with light output from the lens120, for example, by changing the light distribution pattern and/or byblocking portions of the lens 120. The sticky gel may also attract dust,dirt and/or other contaminants that could block or reduce light outputfrom the LED package 100. The gel may also change the shape of theeffective lens, which may modify the emitted light pattern/beam shape.

After placement of the lens 120, the package 100 is typicallyheat-cured, which causes the encapsulant material 112 to solidify andadhere to the lens 120. The lens 120 may, thus, be held in place by thecured encapsulant material 112. However, encapsulant materials having aslight shrinkage factor with curing, such as a silicone gel, generallytend to contract during the heat curing process. In addition, thecoefficient of thermal expansion (CTE) effect generally causes higherfloating of the lens at elevated temperatures. During cool-down, partshave a tendency to delaminate. As the illustrated volume of encapsulantbeneath the lens 120 shown in FIG. 2 is relatively large, thiscontraction may cause the encapsulant material 112 to delaminate (pullaway) from portions of the package 100, including the light emittingdevice 103, a surface of the substrate 102, the sidewalls 105 of thereflector cup 104 and/or the lens 120 during the curing process. Thedelamination may significantly affect optical performance, particularlywhen the delamination is from the die, where it may cause total internalreflection. This contraction may create gaps or voids 113 between theencapsulant material 112 and the light emitting device 103, lens 120,and/or reflector cup 104. Tri-axial stresses in the encapsulant material112 may also cause cohesive tears 113′ in the encapsulant material 112.These gaps 113 and/or tears 113′ may substantially reduce the amount oflight emitted by the light emitting device package 100. The contractionmay also pull out air pockets from crevices (i.e., reflector) or fromunder devices (i.e., die/submount), which may then interfere withoptical cavity performance.

During operation of the lamp, large amounts of heat may be generated bythe light emitting device 103. Much of the heat may be dissipated by thesubstrate 102 and the reflector cup 104, each of which may act as aheatsink for the package 100. However, the temperature of the package100 may still increase significantly during operation. Encapsulantmaterials 112, such as silicone gels, typically have high coefficientsof thermal expansion. As a result, when the package 100 heats up, theencapsulant material 112 may expand. As the lens 120 is mounted within achannel defined by the sidewalls 105 of the reflector cup 104, the lens120 may travel up and down within the sidewalls 105 as the encapsulantmaterial 112 expands and contracts. Expansion of the encapsulantmaterial 112 may extrude the encapsulant into spaces or out of thecavity such that, when cooled, it may not move back into the cavity.This could cause delamination, voids, higher triaxial stresses and/orthe like, which may result in less robust light emitting devices. Suchlens movement is further described, for example, in United States PatentApplication Pub. No. 2004/0041222. The sidewalls 105 may also helpprotect the lens 120 from mechanical shock and stress.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide methods of packaging asemiconductor light emitting device. A first quantity of encapsulantmaterial is dispensed into a cavity including the light emitting device(which may be a plurality of light emitting devices, such as lightemitting diodes), which may be a reflective cavity. The first quantityof encapsulant material in the reflective cavity is treated to form ahardened upper surface thereof having a shape. A luminescent conversionelement is provided on the upper surface of the treated first quantityof encapsulant material. The luminescent conversion element includes awavelength conversion material, such as phosphor and/or nano-crystals,and has a thickness at a middle region of the reflective cavity greaterthan at a region proximate a sidewall of the reflective cavity.

The thickness of the luminescent conversion element may continuouslydecrease as the luminescent conversion element extends radially outwardfrom the middle region to the sidewall. The thickness of the luminescentconversion element may vary by more than ten percent of a maximumthickness of the luminescent conversion element. The luminescentconversion element may have a biconvex, plano-convex or concavo-convexshape.

In other embodiments of the present invention, the methods furtherinclude dispensing a second quantity of encapsulant material onto theluminescent conversion element to form a convex meniscus of encapsulantmaterial in the reflective cavity providing a desired shape of a lens.The second quantity of encapsulant material is cured to form the lensfor the packaged light emitting device from the encapsulant material. Inalternative embodiments, the methods include dispensing a secondquantity of encapsulant material onto the luminescent conversion elementand positioning a lens in the reflective cavity on the dispensed secondquantity of encapsulant material. The dispensed second quantity ofencapsulant material is cured to attach the lens in the reflectivecavity.

In further embodiments of the present invention, providing a luminescentconversion element includes dispensing a second quantity of encapsulantmaterial onto the upper surface of the first quantity of encapsulantmaterial. The second quantity of encapsulant material has the wavelengthconversion material therein. The second quantity of encapsulant materialis cured to define the luminescent conversion element.

In some embodiments of the present invention, the luminescent conversionelement has a biconvex shape. The shape is concave and dispensing andcuring the second quantity of encapsulant material includes dispensingand curing the second quantity of encapsulant material to form a convexupper surface of the second quantity of encapsulant material.

In further embodiments of the present invention, the luminescentconversion element has a plano-convex shape and the shape is concave.Dispensing and curing the second quantity of encapsulant materialincludes dispensing and curing the second quantity of encapsulantmaterial to form a planar upper surface of the second quantity ofencapsulant material. In alternative plano-convex shape embodiments, theshape is planar and dispensing and curing the second quantity ofencapsulant material includes dispensing and curing the second quantityof encapsulant material to form a convex upper surface of the secondquantity of encapsulant material.

In other embodiments of the present invention, the luminescentconversion element has a concavo-convex shape and the shape is convex.Dispensing and curing the second quantity of encapsulant materialincludes dispensing and curing the second quantity of encapsulantmaterial to form a convex upper surface of the second quantity ofencapsulant material. In alternative concavo-convex shape embodiments,the shape is concave and dispensing and curing the second quantity ofencapsulant material includes dispensing and curing the second quantityof encapsulant material to form a concave upper surface of the secondquantity of encapsulant material.

In further embodiments of the present invention, treating the firstquantity of encapsulant material includes curing the first quantity ofencapsulant material. In alternative embodiments, treating the firstquantity of encapsulant material includes pre-curing the first quantityof encapsulant material to form a hardened skin on the upper surfacethereof and the method further comprises curing the first quantity ofencapsulant material after providing the luminescent conversion element.The wavelength conversion material may be phosphor and the firstquantity of encapsulant material is substantially free of phosphor.

In other embodiments of the present invention, the luminescentconversion element is a pre-formed insert and the pre-formed insert isplaced on the upper surface of the treated first quantity of encapsulantmaterial. The pre-formed insert may be a molded plastic phosphor-loadedpiece part. Placing the pre-formed insert on the upper surface may bepreceded by testing the pre-formed insert.

In yet other embodiments of the present invention, packagedsemiconductor light emitting devices include a body, such as areflector, having a lower sidewall portion defining a cavity, which maybe a reflective cavity. A light emitting device is positioned in thecavity. A first quantity of cured encapsulant material is provided inthe cavity including the light emitting device. A luminescent conversionelement is on the upper surface of the first quantity of encapsulantmaterial. The luminescent conversion element includes a wavelengthconversion material and has a thickness at a middle region of the cavitygreater than at a region proximate a sidewall of the cavity. Thethickness of the luminescent conversion element may continuouslydecrease as the luminescent conversion element extends radially outwardfrom the middle region to the sidewall. The thickness of the luminescentconversion element may vary by more than ten percent of a maximumthickness of the luminescent conversion element.

In some embodiments of the present invention, the luminescent conversionelement has a biconvex, plano-convex or concavo-convex shape. The lightemitting device may be a light emitting diode (LED).

In other embodiments of the present invention, the device has a minimumcolor temperature no more than 30 percent below a maximum colortemperature thereof over a 180 (+/−90 from central axis)-degree range ofemission angles. The device may have a primary emission pattern having atotal correlated color temperature (CCT) variation of less than about1000 K over a 180 (+/−90 from central axis)-degree range of emissionangles. In other embodiments, the device has a primary emission patternhaving a total CCT variation of about 500 K over a 180 (+/−90 fromcentral axis)-degree range of emission angles or over a 120 (+/−45 fromcentral axis)-degree range of emission angles. In yet other embodiments,the device has a primary emission pattern having a total correlatedcolor temperature (CCT) variation of less than about 500 K over a 90(+/−45 from central axis)-degree range of emission angles.

In yet further embodiments of the present invention, packagedsemiconductor light emitting devices include a body having a sidewallportion defining a cavity and a light emitting device positioned in thecavity. A first quantity of cured encapsulant material is in the cavityincluding the light emitting device and a luminescent conversion elementis on an upper surface of the first quantity of encapsulant material.The luminescent conversion element includes a wavelength conversionmaterial. The packaged semiconductor light emitting device exhibits avariation of correlated color temperature (CCT)) across a 180 (+/−90from central axis)-degree range of emission angles of less than 2000 K.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are cross-sectional side views illustrating a conventionallight emitting device package;

FIGS. 3A to 3C are cross-sectional side views illustrating methods ofpackaging a light emitting device according to some embodiments of thepresent invention;

FIG. 4A is a top view illustrating a light emitting device packagesuitable for use with some embodiments of the present invention;

FIG. 4B is a cross-sectional side view illustrating the light emittingdevice package of FIG. 4A;

FIG. 5A is a top view illustrating a light emitting device packageaccording to some embodiments of the present invention;

FIG. 5B is a cross-sectional side view illustrating the light emittingdevice package of FIG. 5A;

FIG. 6 is a cross-sectional side view illustrating a light emittingdevice package according to further embodiments of the presentinvention;

FIG. 7 is a cross-sectional side view illustrating a light emittingdevice package according to other embodiments of the present invention;

FIGS. 8A to 8C are cross-sectional side views illustrating methods ofpackaging a light emitting device according to further embodiments ofthe present invention;

FIGS. 9A to 9C are cross-sectional side views illustrating methods ofpackaging a light emitting device according to other embodiments of thepresent invention;

FIGS. 10A to 10C are cross-sectional side views illustrating methods ofpackaging a light emitting device according to yet further embodimentsof the present invention;

FIG. 11 is a flowchart illustrating operations for packaging a lightemitting device according to some embodiments of the present invention;

FIG. 12 is a flowchart illustrating operations for packaging a lightemitting device according to some other embodiments of the presentinvention;

FIG. 13 is a flowchart illustrating operations for packaging a lightemitting device according to yet further embodiments of the presentinvention;

FIG. 14 is a schematic diagram illustrating path length for lighttraveling through a layer;

FIG. 15 is a polar plot of color-temperature for a light emitting diode(LED) emission pattern;

FIGS. 16A to 16C are cross-sectional side views illustrating methods ofpackaging a light emitting device including a luminescent conversionelement according to further embodiments of the present invention;

FIGS. 17A to 17C are cross-sectional side views illustrating methods ofpackaging a light emitting device including a luminescent conversionelement according to other embodiments of the present invention;

FIGS. 18A to 18C are cross-sectional side views illustrating methods ofpackaging a light emitting device including a luminescent conversionelement according to some other embodiments of the present invention;

FIG. 19 is a flowchart illustrating operations for packaging a lightemitting device according to some further embodiments of the presentinvention;

FIG. 20A is a polar plot of color-temperature for a light emitting diode(LED) emission pattern for a glob-top semiconductor light emittingdevice without a luminescence conversion element of the presentinvention;

FIG. 20B is a polar plot of color-temperature for a light emitting diode(LED) emission pattern for a semiconductor light emitting device with aluminescence conversion element according to some embodiments of thepresent invention;

FIGS. 21A and 21B are digitally analyzed plots of the near fieldemission pattern of packaged semiconductor light emitting device withouta luminescence conversion element; and

FIGS. 22A and 22B are digitally analyzed plots of the near fieldemission pattern of packaged semiconductor light emitting deviceincluding a luminescence conversion element according to someembodiments of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, the size and relative sizes of layers and regions may beexaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element such as a layer, region orsubstrate is referred to as being “on” another element, it can bedirectly on the other element or intervening elements may also bepresent. It will be understood that if part of an element, such as asurface, is referred to as “inner,” it is farther from the outside ofthe device than other parts of the element. Furthermore, relative termssuch as “beneath” or “overlies” may be used herein to describe arelationship of one layer or region to another layer or region relativeto a substrate or base layer as illustrated in the figures. It will beunderstood that these terms are intended to encompass differentorientations of the device in addition to the orientation depicted inthe figures. Finally, the term “directly” means that there are nointervening elements. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Various embodiments of the present invention for packaging asemiconductor light emitting device 103 will be described herein. Asused herein, the term semiconductor light emitting device 103 mayinclude a light emitting diode, laser diode and/or other semiconductordevice which includes one or more semiconductor layers, which mayinclude silicon, silicon carbide, gallium nitride and/or othersemiconductor materials, a substrate which may include sapphire,silicon, silicon carbide and/or other microelectronic substrates, andone or more contact layers which may include metal and/or otherconductive layers. In some embodiments, ultraviolet, blue and/or greenlight emitting diodes (“LEDs”) may be provided. Red and/or amber LEDsmay also be provided. The design and fabrication of semiconductor lightemitting devices 103 are well known to those having skill in the art andneed not be described in detail herein.

For example, the semiconductor light emitting device 103 may be galliumnitride-based LEDs or lasers fabricated on a silicon carbide substratesuch as those devices manufactured and sold by Cree, Inc. of Durham,N.C. The present invention may be suitable for use with LEDs and/orlasers as described in U.S. Pat. Nos. 6,201,262; 6,187,606; 6,120,600;5,912,477; 5,739,554; 5,631,190; 5,604,135; 5,523,589; 5,416,342;5,393,993; 5,338,944; 5,210,051; 5,027,168; 5,027,168; 4,966,862 and/or4,918,497, the disclosures of which are incorporated herein by referenceas if set forth fully herein. Other suitable LEDs and/or lasers aredescribed in published U.S. Patent Publication No. US 2003/0006418 A1entitled Group III Nitride Based Light Emitting Diode Structures With aQuantum Well and Superlattice, Group III Nitride Based Quantum WellStructures and Group III Nitride Based Superlattice Structures,published Jan. 9, 2003, as well as published U.S. Patent Publication No.US 2002/0123164 A1 entitled Light Emitting Diodes IncludingModifications for Light Extraction and Manufacturing Methods Therefor.Furthermore, phosphor coated LEDs, such as those described in U.S.application Ser. No. 10/659,241, entitled Phosphor Coated Light EmittingDiodes Including Tapered Sidewalls and Fabrication Methods Therefor,filed Sep. 9, 2003, the disclosure of which is incorporated by referenceherein as if set forth fully, may also be suitable for use inembodiments of the present invention. The LEDs and/or lasers may beconfigured to operate such that light emission occurs through thesubstrate. In such embodiments, the substrate may be patterned so as toenhance light output of the devices as is described, for example, in theabove-cited U.S. Patent Publication No. US 2002/0123164 A1.

Embodiments of the present invention will now be described withreference to the various embodiments illustrated in FIGS. 3-11. Moreparticularly, some embodiments of a double-cure encapsulation processfor use in packaging a light emitting device 103 are illustrated inFIGS. 3A through 3C. Such a double cure encapsulation process may reduceproblems associated with shrinkage of encapsulant material duringcuring. As will be described herein, for some embodiments of the presentinvention, the double cure process may include three dispense operationsand two cure operations. However, it will be understood that more orless dispense operations and cure operations may also be used inpackaging the light emitting device in other embodiments of the presentinvention. As will also be further described herein, embodiments of thepresent invention also include a multi-dispense operation, leading to afirst cure operation followed by another set of dispense and cureoperations to attach a lens.

As illustrated in FIG. 3A, a first predetermined amount (quantity) of anencapsulant material, including two encapsulant material portions 112,114 in the illustrated embodiments, is dispensed within the cavity 115.The encapsulant material 112, 114 may be, for example, a liquid silicongel, an epoxy or the like. The first portion 112 may be dispensed to wetexposed surface portions of the light emitting device 103, moreparticularly, the led chip/submount assembly 101 of the light emittingdevice 103, and the substrate 102. Portions of the reflector cup 104 mayalso be wet by the initial dispense. In some embodiments of the presentinvention, the quantity of encapsulant material dispensed as the firstportion 112 is sufficient to wet the light emitting device 103 withoutfilling the reflective cavity to a level exceeding the height of thelight emitting device 103. In some other embodiments of the presentinvention, the quantity of encapsulant material dispensed as the firstportion 112 is sufficient to substantially cover the light emittingdevice 103 without forming any air pockets in the encapsulant material112.

As shown in FIG. 3A, the light emitting device is positioned at about amidpoint 115 m of the reflective cavity 115. The encapsulant materialmay be dispensed from a dispenser 200 at a point 115 d displaced fromthe midpoint 115 m towards a sidewall 105 of the reflective cavity 115so that the encapsulant material 112 is not dispensed directly onto thelight emitting device 103. Dispensing encapsulant material 112 directlyon the light emitting device 103 may cause trapping of bubbles as theencapsulant material 112 passes over the structure of the light emittingdevice 103 from above. However, in other embodiments of the presentinvention, the encapsulant material 112 is dispensed on top of the lightemitting device 103 die in addition to or instead of an offset dispense.Dispensing the encapsulant material 112 may include forming a bead ofthe encapsulant material 112 on an end of a dispenser 200 and contactingthe formed bead with the reflective cavity 115 and/or the light emittingdevice 103 to dispense the bead from the dispenser.

The viscosity and/or other properties of the material used for adispense may be selected such that, for example, wetting occurs withoutbubble formation. In further embodiments of the present invention,coatings may be applied to surfaces contacted by the dispensed materialto speed/retard the wetting rate. For example, using certain knowncleaning procedures that leave microscopic residue, such as an oil film,selected surfaces may be treated and, thus, used to engineer thedynamics of the wetting action.

Due to the surface properties of the inner surface of the reflector cup104 defining the cavity 115, of the light emitting device 103 and of theencapsulant material 112, dispensed encapsulant material 112, even whendispensed from a point 115 d displaced from the midpoint 115 m of thecavity 115, may flow within the cavity 115 in a manner that could stillcause bubbles in the encapsulant material 112. In particular, theencapsulant material 112 is expected to move or “wick” more rapidlyaround the inner surface of the reflector cup 104 and the sidewalls ofthe light emitting device 103 faster than over the top of the lightemitting device 103. As a result, a bubble could be trapped on a side ofthe cavity 115 opposite from the side where the encapsulant material isdispensed when the side flowing encapsulant material meets and thenencapsulant material flows over the top of the light emitting device103, thus being locally dispensed from above with no side outlet for airflow. Accordingly, the quantity of the first portion of dispensedencapsulant material 112 may be selected to reduce or prevent the riskof forming such bubbles. As such, as used herein, reference to“substantially” covering the light emitting device 103 refers tocovering enough of the structure of the light emitting device 103 sothat such a bubble will not result when the remaining portion 114 of thefirst quantity of encapsulant material 112, 114 is dispensed.

After the initially dispensed encapsulant material 112 is allowed tosettle, the second portion 114 of the first predetermined quantity ofencapsulant material is dispensed into the reflective cavity 115. Thesecond portion 114 of the encapsulant material, in some particularembodiments of the present invention, is about twice the first portion112.

After dispensing all the first quantity of encapsulant material 112,114, the first quantity of the encapsulant material 112, 114 is cured,for example, by a heat treatment, to solidify the encapsulant material112, 114. After curing, the level of the encapsulant material 112, 114within the reflective cavity 115 may drop from the level 114A to thelevel 114B as a result of shrinkage of the encapsulant material 112,114.

In some embodiments of the present invention, the first portion 112 iscured before the second portion 114 is dispensed into the reflectivecavity 115. For example, it is known to add a light converting material,such as a phosphor, nano-crystals, or the like, to the encapsulantmaterial 112, 114 to affect the characteristics of the light emittedfrom the package 100. For purposes of the description herein, referenceswill be made to a phosphor as a light converting material. However, itwill be understood that other light converting materials may be used inplace of phosphor. Depending on the desired color spectrum and/or colortemperature tuning for the package 100, phosphor may be mostbeneficially utilized when positioned adjacent the emitter 103 b, inother words, directly on top of the light emitting device 103. As such,it may be desirable to include a phosphor in the second portion 114while not including a phosphor in the first portion 112. However, as thefirst portion 112 is below the second portion 114, phosphor may settlefrom the second portion 114 into the first portion 112, reducing theeffectiveness of the phosphor addition in the second portion 114.Accordingly, phosphor can be added to the first portion 112 to limitsuch settling and/or the first portion 112 can be cured beforedispensing the second portion 114. The use of multiple dispenses mayalso allow the addition of a phosphor preform/wafer of a desiredconfiguration for light conversion. In addition, multiple dispenses mayallow for the use of materials having different indexes of refraction toprovide, for example, a buried lens (i.e., formed by the interfacebetween two dispenses of materials with different refractive indexes).

As illustrated in FIG. 3B, a second quantity of encapsulant material 116is dispensed in a predetermined amount onto the cured first quantity ofencapsulant material 112, 114 in the reflective cavity 115. In someparticular embodiments of the present invention the second quantity 116is about equal to the first portion 112 of the first quantity ofencapsulant material 112, 114. The second quantity 116 may besubstantially free of phosphor, however, in other embodiments of thepresent invention, phosphor may also be included in the second quantity116.

As shown in FIG. 3C, before the second quantity of encapsulant material116 is cured, a lens 120 is positioned within the reflective cavity 115and against the second quantity of encapsulant material 116. The secondquantity of encapsulant material 116 is then cured, for example, byheating, to harden the encapsulant material 116 and to attach the lens120 in the reflective cavity 115. In some embodiments of the presentinvention, use of a double cure process as described above toencapsulate the light emitting device 103 in the package 100 may reducedelamination of the cured encapsulant material 112, 114, 116 from thelight emitting device 103, the lens 120 and/or the reflector cup 104.

The reflector cup 104 shown in FIGS. 3A-3B is further illustrated inFIGS. 4A-4B. FIG. 4A is a top plan view of the reflector cup 104 showingthe top surfaces of the upper sidewall 105, the lower sidewall 106 and asubstantially horizontal shoulder sidewall portion 108 between the uppersidewall 105 and the lower sidewall 106. FIG. 4B is a cross-sectionalview of the reflector cup 104 taken along line B-B of FIG. 4A.

Alternative reflector cup configurations according to variousembodiments of the present invention will now be described as well asmethods for packaging of a light emitting device using such alternativereflector cup configurations. In various embodiments of the presentinvention, these alternative reflector cup configurations may reduce theincidence and/or amount of squeeze out of encapsulant material oninsertion of a lens into encapsulant material in the reflector cup.FIGS. 5A-5B, 6 and 7 illustrate various alternative reflectorconfigurations as will now be described. FIG. 5A is a top plan view of areflector cup 4 and FIG. 5B is a cross-sectional view of the reflectorcup 4 taken along line B-B of FIG. 5A. FIG. 6 is a cross-sectional viewof a reflector cup 4A and FIG. 7 is a cross-sectional view of areflector cup 4B. Each of the illustrated reflector cups 4, 4A, 4Bincludes an upper sidewall 5, an angled lower sidewall 6 and ahorizontal shoulder portion 8 between the upper sidewall 5 and the lowersidewall 6, together defining a reflective cavity 15. As used hereinwith reference to the shoulder portion 8, “horizontal” refers to thegeneral direction in which the shoulder portion 8 extends between thelower sidewall portion 6 and the upper sidewall portion 8 (i.e., ascompared to the lower 6 and upper 5 sidewall portions), not to theparticular angle of the shoulder portion 8 at any intermediate portionthereof (see, e.g., FIG. 7 where the horizontal shoulder portion mayactually have some change in vertical height between the lower 6 andupper 5 sidewall portions to accommodate other features thereof). Inaddition, each of the reflector cups 4, 4A, 4B may include at least onemoat 18 surrounding the lower sidewall 6, with the moat 18 beingseparated from the lower sidewall 6 by a lip (i.e., a projecting edge)22. The moat 18 is illustrated as formed in the shoulder portion 8.

In the embodiments of FIGS. 5A-5B, the moat 18 could be formed bystamping, in which case the lip 22 between the moat 18 and the lowersidewall 6 may be provided with a sharp edge instead of a flat surface.However, it will be understand that, due to the limitations of thefabricating processes used, the flat surface of the lip 22 schematicallyillustrated in FIG. 5B may actually have a more rounded profile. Toomuch of a rounded profile may be undesirable as will be furtherdescribed with reference to FIGS. 8A-8C.

Further embodiments of a reflector cup 4A will now be described withreference to the cross-sectional view of FIG. 6. As shown in FIG. 6, afirst moat 18 is formed between the upper sidewall 5 and the lowersidewall 6, with a first or inner lip 22 separating the lower sidewall 6and the first moat 18. A second moat 24 is formed between the uppersidewall 5 and the first moat 18. A second or outer lip 26 separates thesecond moat 24 from the first moat 18.

Yet further embodiments of a reflector cup 4B will now be described withreference to the cross-sectional view of FIG. 7. As shown in FIG. 7, afirst moat 18 is formed between the upper sidewall 5 and the lowersidewall 6, with a first or inner lip 22 separating the lower sidewall 6and the first moat 18. A second moat 24 is formed between the uppersidewall 5 and the first moat 18. A second or outer lip 26′ separatesthe second moat 24 from the first moat 18. As illustrated in FIG. 7, thesecond lip 26′ is elevated with respect to the first lip 22.

In particular embodiments of the present invention, the first lip 22 hasa peak having a radius of curvature of less than about 50 micrometers(μm) and the second lip 26, 26′ has a peak having a radius of curvatureof less than about 50 μm. The first moat 18 and the second moat 24 maybe stamped features of the horizontal shoulder portion 8. As shown inFIGS. 6 and 7, the second moat 24 may have a width extending from thesecond lip 26, 26′ to the upper sidewall portion 5.

In some embodiments of the present invention, the sloped lower sidewallportion 6 may be substantially conical and may have a minimum diameterof from about 1.9 millimeters (mm) for a 500 μm light emitting devicechip to about 3.2 mm for a 900 μm light emitting device chip and amaximum diameter of from about 2.6 mm for a 500 μm light emitting devicechip to about 4.5 mm for a 900 μm light emitting device chip and aheight of from about 0.8 mm to about 1.0 mm. The upper sidewall portionmay be substantially oval and have an inner diameter of from about 3.4mm to about 5.2 mm and a height of from about 0.6 mm to about 0.7 mm.The horizontal shoulder portion may have a width from the lower sidewallportion to the upper sidewall portion of from about 0.4 mm to about 0.7mm. It will be understood that, as used herein, the terms “oval” and“conical” are intended to encompass circular, cylindrical and othershapes, including irregular shapes based on the fabrication technologyused to form the reflector cup 4, 4A, 4B that may, nonetheless, incombination with a substrate 2 or otherwise, operate to provide areflector for the light emitting device 103 and retain and harden anencapsulant material 12, 14, 16 therein.

In some embodiments of the present invention, the first moat 18 has awidth from about 0.3 mm to about 0.4 mm and the second moat 24 has awidth of from about 0.3 mm to about 0.4 mm. As illustrated in FIG. 6,the edge of the first moat 18 may be a first lip 22 having a heightrelative to a bottom end (i.e., a top surface of the substrate 2) of thelower sidewall portion 6 of from about 0.79 mm to about 0.85 and theedge of the second moat 24 may be a second lip 26 having a heightrelative to bottom end of the lower sidewall portion 6 of from about0.79 mm to about 0.85 mm. In other embodiments of the present inventionas illustrated in FIG. 7, the first lip 22 has a height relative to abottom end of the lower sidewall portion of from about 0.79 mm to about0.85 mm and the second lip 26′ has a height relative to a bottom end ofthe lower sidewall portion of from about 0.9 mm to about 1.0 mm.

The reflector cups 4, 4A, 4B, in various embodiments of the presentinvention may, provide for meniscus control when packaging the lightemitting device 103 in a reflector cup 4, 4A, 4B. As will be furtherdescribed, when combined with the double cure methods described above, adistinct convex meniscus may also be provided for different dispenses ofencapsulant material and, as a result, the incidence of doming failuremay be reduced. In other embodiments of the present invention, theprovided meniscus control may reduce the difficulty of lens placement ata desired depth and/or angle, reduce lens wicking or squeeze-out ofencapsulant material onto the top of the lens and/or allow forconfiguration of the optical characteristics of the packaged lightemitting device. For example, phosphor may be concentrated in the center(midpoint) of the package by doming (convex meniscus) of phosphor loadedencapsulant material over the midpoint of the package.

Different optical patterns (viewing angles, custom color spectrums,color temperature tuning and the like) may be provided by using multiplemeniscus control techniques in combination with dispensing and/or curingvariations in the process. For example, a high peaked dome of a phosphorloaded material may provide greater color spectrum uniformity of whitetemperature light emission with less shift to yellow towards the edgesof the reflector cup by providing a more uniform length of the lightpath through the phosphor loaded material from the light emittingdevice. Similarly, where desired, a greater color spectrum variationfrom white at the midpoint to yellow at the edges may be provided by aflatter dome. In some other embodiments of the present invention, whereprotection related functionality is provided by features other than alens, meniscus control may allow for packaging a light emitting devicewithout a lens by using the encapsulant material as the lens, with themeniscus being configured to provide the desired lens shape.

FIGS. 8A-8C illustrate methods of packaging a light emitting device,using the structural characteristics of a reflector cup for meniscuscontrol, according to some embodiments of the present invention. Theoperations illustrated in FIGS. 8A-8C utilize the reflector cup 4illustrated in FIGS. 5A-5B and the double curing operations alsopreviously described. As shown in FIG. 8A, a first quantity 14 ofencapsulant material is deposited in the reflective cavity 15 of thepackage 10A. In some embodiments of the present invention, the firstquantity 14 may be dispensed using a separate (wetting) dispense andsecond dispense. With proper control of the amount of encapsulantmaterial dispensed, surface tension will cause the liquid encapsulantmaterial 14 to cling to the lip 22, forming a convex meniscus asillustrated in FIG. 8A at a height indicated at 14A. Thus, the lip 22may be used to prevent the dispensed encapsulant material 14 fromcontacting and wicking up the upper sidewall 5 and forming a concavemeniscus as shown in FIG. 1.

The dispensed encapsulant material 14 is cured, for example, by heating,and may shrink down to a height indicated at 14B. As shown in FIG. 8B, asecond quantity 16 of encapsulant material is then dispensed into thecavity 15 on the cured first quantity 14 of encapsulant material. Insome embodiments, as illustrated in FIG. 8B, the second quantity 16 ofencapsulant material may also cling to the same edge of the lip 22 toform a convex meniscus. In other embodiments, the lip 22 may have aninner and outer edge thereon and the second quantity 16 of encapsulantmaterial may cling to the outer edge and the first quantity 14 may clingto the inner edge. Thus, the second quantity 16 of encapsulant materialmay also not contact or wick up the upper sidewall 5 to form a concavemeniscus.

Referring to FIG. 8C, the lens 20 is inserted into reflective cavity 15and brought into contact with the uncured liquid encapsulant material16. As such, the encapsulant material 16 may be squeezed out fromunderneath the lens 20. However, in some embodiments of the presentinvention, instead of squeezing out onto the exposed upper surfaces ofthe reflector cup and the lens (as shown in FIG. 2), the excess of theencapsulant material 16 is squeezed into and received by the moat 18,thus limiting wicking of the encapsulant material 16 up the sidewall 5even after the lens 20 is inserted and the convex meniscus shown in FIG.8B is displaced. The encapsulant material 16 is then cured to attach thelens 20 in the package 10A and to solidify the encapsulant material 16.

FIGS. 9A-9C illustrate methods of packaging a light emitting device,using the structural characteristics of a reflector cup for meniscuscontrol, according to some embodiments of the present invention. Theoperations illustrated in FIGS. 9A-9C utilize the reflector cup 4Aillustrated in FIG. 6 and the double curing operations also previouslydescribed. As shown in FIG. 9A, a first quantity 14 of encapsulantmaterial is deposited in the reflective cavity 15 of the package 10B. Insome embodiments of the present invention, the first quantity 14 may bedispensed using a distinct first (wetting) dispense and a seconddispense after wetting of the light emitting device. With proper controlof the amount of encapsulant material dispensed, surface tension willcause the liquid encapsulant material 14 to cling to the inner lip 22,forming a convex meniscus as illustrated in FIG. 9A at a heightindicated at 14A. Thus, the inner lip 22 may be used to prevent thedispensed encapsulant material 14 from contacting and wicking up theupper sidewall 5 and forming a concave meniscus as shown in FIG. 1.

The dispensed encapsulant material 14 is cured, for example, by heating,and may shrink down to a height indicated at 14B. As shown in FIG. 9B, asecond quantity 16 of encapsulant material is then dispensed into thereflective cavity 15 on the cured first quantity 14 of encapsulantmaterial. In some embodiments, as illustrated in FIG. 9B, the secondquantity 16 of encapsulant material clings to the outer lip 26, forminga convex meniscus. Thus, the outer lip 26 may be used to prevent thedispensed second quantity 16 of encapsulant material from contacting andwicking up the upper sidewall 5 and forming a concave meniscus as shownin FIG. 1.

Referring to FIG. 9C, the lens 20 is inserted into reflective cavity 15and brought into contact with the uncured liquid encapsulant material16. As such, the encapsulant material 16 may be squeezed out fromunderneath the lens 20. However, in some embodiments of the presentinvention, instead of squeezing out onto the exposed upper surfaces ofthe reflector cup and the lens (as shown in FIG. 2), the excess of theencapsulant material 16 is squeezed into and received by the second moat24, thus limiting wicking of the encapsulant material 16 up the sidewall5 even after the lens 20 is inserted and the convex meniscus shown inFIG. 9B is displaced. The encapsulant material 16 is then cured toattach the lens 20 in the package 10B and to solidify the encapsulantmaterial 16.

FIG. 9C further illustrates that, in some embodiments of the presentinvention, the cured encapsulant 14 may be used as a stop to provide forlevel (depth of placement) control for the lens 20. Such control overthe positioning of the lens 20 may facilitate the production of partswith more consistent optical performance.

As shown in FIG. 9C, the lens 20 in some embodiments of the present ispositioned without advancing into the cavity until it contacts the curedfirst quantity of encapsulant material 14 as a film of the encapsulantmaterial 16 remains therebetween. Thus, in some embodiments of thepresent invention, the device is configured so that the lens 20 may beadvanced to a position established by the first quantity of encapsulantmaterial 14, which position may be established with or without contactof the lens 20 to the cured encapsulant material 14 in variousembodiments of the present invention.

FIGS. 10A-10C illustrate methods of packaging a light emitting device,using the structural characteristics of a reflector cup for meniscuscontrol, according to some embodiments of the present invention. Theoperations illustrated in FIGS. 10A-10C utilize the reflector cup 4Billustrated in FIG. 7 and the double curing operations also previouslydescribed. As shown in FIG. 10A, a first quantity 14 of encapsulantmaterial is deposited in the reflective cavity 15 of the package 10C. Insome embodiments of the present invention, the first quantity 14 may bedispensed using a separate (wetting) dispense and a second dispense.With proper control of the amount of encapsulant material dispensed,surface tension will cause the liquid encapsulant material 14 to clingto the inner lip 22, forming a convex meniscus as illustrated in FIG.10A at a height indicated at 14A. Thus, the inner lip 22 may be used toprevent the dispensed encapsulant material 14 from contacting andwicking up the upper sidewall 5 and forming a concave meniscus as shownin FIG. 1.

The dispensed encapsulant material 14 is cured, for example, by heating,and may shrink down to a height indicated at 14B. As shown in FIG. 10B,a second quantity 16 of encapsulant material is then dispensed into thereflective cavity 15 on the cured first quantity 14 of encapsulantmaterial. In some embodiments, as illustrated in FIG. 10B, the secondquantity 16 of encapsulant material clings to the outer lip 26′, forminga convex meniscus. Thus, the outer lip 26′ may be used to prevent thedispensed second quantity 16 of encapsulant material from contacting andwicking up the upper sidewall 5 and forming a concave meniscus as shownin FIG. 1.

Referring to FIG. 10C, the lens 20 is inserted into reflective cavity 15and brought into contact with the uncured liquid encapsulant material16. As such, the encapsulant material 16 may be squeezed out fromunderneath the lens 20. However, in some embodiments of the presentinvention, instead of squeezing out onto the exposed upper surfaces ofthe reflector cup and the lens (as shown in FIG. 2), the excess of theencapsulant material 16 is squeezed into and received by the second moat24, thus limiting wicking of the encapsulant material 16 up the sidewall5 even after the lens 20 is inserted and the convex meniscus shown inFIG. 10B is displaced. The encapsulant material 16 is then cured toattach the lens 20 in the package 10C and to solidify the encapsulantmaterial 16.

FIG. 10C further illustrates that, in some embodiments of the presentinvention, the outer lip 26′ may be used as a stop to provide for level(depth of placement) control for the lens 20. Such control over thepositioning of the lens 20 may facilitate the production of parts withmore consistent optical performance. In this embodiment, the lensplacement does not depend on the amount of shrinkage of the encapsulantduring the first cure step. For the embodiments illustrated in FIG. 10C,as contrasted with those illustrated in FIG. 9C, the placement of thelens 20 need not be dependent on the amount of shrinkage of the firstquantity 14 of encapsulant material as the placement depth is, instead,defined by the height of the outer lip 26′. As such, in some embodimentsof the present invention, the placement may be more exact, which mayresult in improved optical performance of the package 10C.

Methods for packaging a light emitting device using a first (wetting)dispense according to some embodiments of the present invention will nowbe further described with reference to the flowchart illustrations ofFIG. 11. As shown in FIG. 11, operations may begin at Block 1100 bymounting the light emitting device on a bottom surface of a reflectivecavity. The mounted light emitting device has an associated heightrelative to the bottom surface of the reflective cavity. A firstquantity of encapsulant material is dispensed into the reflective cavityincluding the light emitting device (Block 1120).

The first quantity may be sufficient to substantially cover the lightemitting device without forming any air pockets in the encapsulantmaterial. In some embodiments of the present invention, the firstquantity may be sufficient to wet the light emitting device withoutfilling the reflective cavity to a level exceeding the height of thelight emitting device. In other embodiments of the present invention,the time/speed of dispense of the encapsulant material may be changed toreduce the formation of air pockets in the encapsulant material. In yetfurther embodiments, a single dispense may be used, for example, with aslow dispense rate, from a small dispense needle, low pressure, or thelike, allowing an air pocket to potentially form and then cave/collapsebefore enough encapsulant material has been dispensed to preventcollapse of the air pocket. Thus, the first (wetting) dispense andsecond dispense may be provided by a continuous dispense at a selectedrate of a selected viscosity encapsulant material that allowscave/collapse of a formed air pocket during the dispense operation Thefirst quantity may be sufficient to wet the light emitting devicewithout filling the reflective cavity to a level exceeding the height ofthe light emitting device.

A second quantity of encapsulant material is dispensed onto the firstquantity of encapsulant material (Block 1130). The dispensed first andsecond quantity of encapsulant material are then cured (Block 1140). Insome embodiments of the present invention, the first dispensed wettingquantity of encapsulant material may be cured before the remainder ofthe encapsulant material is dispensed.

The first quantity 12, 14 and the second quantity 16 of the encapsulantmaterial may be the same or different materials. Similarly, the first 12and second 14 portions of the first quantity of the encapsulant materialmay be the same or different materials. Examples of materials that maybe used as an encapsulant material in various embodiments of the presentinvention include silicon.

Operations related to packaging a semiconductor light emitting deviceaccording to some embodiments of the present invention using meniscuscontrol will now be described with reference to the flowchartillustration of FIG. 12. As shown in FIG. 12, operations may begin atBlock 1200 with mounting of the light emitting device 103 in areflective cavity 15 of a reflector 5. Encapsulant material is dispensedinto the reflective cavity 15 including the light emitting device 103therein to cover the light emitting device 103 and to form a convexmeniscus of encapsulant material in the reflective cavity extending froman edge of the moat without contacting the upper sidewall 5 of thereflector 4, 4A, 4B (Block 1210). More generally, operations at Block1210 provide for formation of a convex meniscus extending from an outeredge of the meniscus that is at a height positioning the outer edge ofthe meniscus within the reflective cavity 15. For example, selection ofmaterials used for the upper sidewall 5 and the encapsulant material 12,14, 16 may facilitate formation of a convex, rather than concave,meniscus extending into the reflective cavity 15. The encapsulantmaterial 12, 14, 16 is in the reflective cavity 15 (Block 1220). Inembodiments where a lens 20 is included in the package 10A, 10B, 10C,insertion of the lens 20 may include collapsing the convex meniscus andmoving a portion of the encapsulant material 12, 14, 16 into the moat18, 24 with the lens 20 and then curing the encapsulant material 12, 14,16 to attach the lens 20 in the reflective cavity 15. Alternatively, theencapsulant material 12, 14, 16 may be cured to form a lens for thepackaged light emitting device 103 from the encapsulant material 12, 14,16 and the encapsulant material 12, 14, 16 may be dispensed to form aconvex meniscus providing a desired shape of the lens.

Embodiments of methods of packaging a semiconductor light emittingdevice 103 in a reflector 4, 4A, 4B having a moat 18, 24 positionedbetween a lower 6 and an upper 5 sidewall thereof, the upper 5 and lower6 sidewall defining a reflective cavity 15, using a multiple dispenseand/or cure operation will now be further described with reference toFIG. 13. As shown in the embodiments of FIG. 13, operations begin atBlock 1300 by dispensing a first quantity 14 of encapsulant materialinto the reflective cavity 15 to form a first convex meniscus. The firstquantity 14 of encapsulant material is cured (Block 1310). A secondquantity 16 of encapsulant material is dispensed onto the cured firstquantity 14 of encapsulant material to form a second convex meniscus ofencapsulant material in the reflective cavity 15 extending from an edgeof the moat 18, 24 without contacting the upper sidewall 5 of thereflector 4, 4A, 4B (Block 1320).

The second convex meniscus and the first convex meniscus of encapsulantmaterial may both extend from the same edge of the moat 18 asillustrated in FIG. 8B. However, in other embodiments of the presentinvention, the moat 18, 24 may have an inner edge and an outer edge,such as the first lip 22 and the second lip 26, 26′, and the secondconvex meniscus of encapsulant material extends from the outer edge(second lip 26, 26′) of the moat 18, 24 and the first convex meniscus ofencapsulant material extends from the inner edge (first lip 22) of themoat 18, 24. Thus, using the first lip 22, the inner moat 18 may beconfigured to limit wicking of encapsulant material 14 outwardly alongthe horizontal shoulder portion 8 to allow formation of a first convexmeniscus of encapsulant material dispensed into the reflective cavity15. Using the second lip 26, 26′, the outer moat 24 may be configured tolimit wicking of encapsulant material outwardly along the horizontalshoulder portion 8 to allow formation of a second convex meniscus ofencapsulant material dispensed into the reflective cavity 15.

In some embodiments of the present invention including a lens, the lens20 is positioned in the reflective cavity 15 proximate the dispensedsecond quantity 16 of encapsulant material (Block 1330). Positioning thelens 20 may include collapsing the second convex meniscus and moving aportion of the second quantity 16 of encapsulant material into the outermoat 24 with the lens 20 as illustrated in FIGS. 9C and 10C. Inaddition, as illustrated in FIG. 10C, the second lip 26′ may have aheight greater than that of the first lip 22. The height of the secondlip 26′ may be selected to provide a desired position for the lens 20and the lens 20 may be moved into the reflective cavity 15 until itcontacts the second lip 26′. In other embodiments of the presentinvention, as illustrated in FIG. 9C, the lens 20 is advanced into thereflective cavity 15 until it contacts the cured first quantity 14 ofencapsulant material and the dispensed first quantity 14 of encapsulantmaterial sufficient to establish a desired position for the lens 20 inthe reflective cavity 15. The dispensed second quantity 16 ofencapsulant material is cured to attach the lens 20 in the reflectivecavity 15 (Block 1340).

The flowcharts of FIGS. 11-13 and the schematic illustrations of FIGS.8A-8C, 9A-9C and 10A-10C illustrate the functionality and operation ofpossible implementations of methods for packaging a light emittingdevice according to some embodiments of the present invention. It shouldbe noted that, in some alternative implementations, the acts noted indescribing the figures may occur out of the order noted in the figures.For example, two blocks/operations shown in succession may, in fact, beexecuted substantially concurrently, or may be executed in the reverseorder, depending upon the functionality involved.

As discussed above, different optical patterns (viewing angles, customcolor spectrums, color temperature tuning and the like) may be providedby using multiple meniscus control techniques in combination withdispensing and/or curing variations in the process. For example, a highpeaked dome of a phosphor loaded material may provide greater colorspectrum uniformity of white temperature light emission with less shiftto yellow towards the edges of the reflector cup by providing a moreuniform length of the light path through the phosphor loaded materialfrom the light emitting device.

Embodiments of the present invention provide one or more light emittingdevices (i.e. chips) mounted in an optical cavity with a phosphor-loadedluminescent conversion layer formed in proximity to the light emittingdevice (i.e. adjacent or in a spaced relationship thereto). Conventionalpackaging technology teaches that the luminescent conversion layershould have a thickness variation less than or equal to ten percent(10%) of the average thickness of the luminescent conversion layer.However, such a requirement means that light emission from the opticalcavity may travel substantially different path lengths through theluminescent conversion layer depending on the angle of emission,resulting in non-uniform wavelength conversion (and thereforenon-uniform correlated color temperature or CCT) as a function ofviewing angle. For example, light traveling in a direction normal to aluminescent conversion layer having a thickness t will travel throughthe luminescent conversion layer by a path length (PL) equal to t, theshortest possible path length. However, as shown schematically in FIG.14, light emitted by a light emitting device 103 and passing through theluminescent conversion layer at an angle of incidence α has a pathlength equal to the thickness t divided by the cosine of the angle ofincidence. Thus, for example, light passing through a luminescentconversion layer at an angle of incidence of 60° would travel throughthe layer by a path length that is twice the path length of lighttraveling in a normal direction. FIG. 15 is a polar plot of an emissionpattern showing substantial sidelobes at off-axis angles of emissionthat may result from a conventional glob-top type semiconductor lightemitting device including a light emitting diode (LED).

The methods disclosed herein for meniscus control may be employed toform a shaped luminescent conversion region or element that may resultin improved color uniformity. Improved color uniformity may bequantified, for example, by improved angular uniformity of correlatedcolor temperature or reduced variation in CCT across all viewing angles.Alternatively, the improved uniformity is evidenced by near fieldoptical measurements as a reduced spatial CCT variation across theemission surface of the LED.

In some embodiments, a phosphor-loaded luminescent conversion region orelement is characterized by a non-uniform thickness that is greater inthe middle of the optical cavity and smaller near the sidewalls of theoptical cavity. In some embodiments, a phosphor-loaded luminescentconversion region or element is thickest at the center of the opticalcavity and becomes thinner as it extends radially outward toward theedge of the luminescent conversion region. In some embodiments, thethickness variation of the phosphor-loaded luminescent conversion regionis greater than 10% of the maximum thickness of the luminescentconversion region. In some embodiments, the luminescent conversionregion or element is shaped in the form of a biconvex, plano-convex orconcavo-convex region. In some embodiments, the luminescent conversionelement comprises a pre-formed structure, such as a molded plasticphosphor-loaded piece part, that is inserted into the reflective cavityof the package.

Embodiments of the invention in which the phosphor-loaded region isshaped to provide improved color uniformity are shown in FIGS. 16A-16C,which illustrate methods of packaging a light emitting device andresulting devices using the structural characteristics of a reflectorcup for meniscus control. The operations illustrated in FIGS. 16A-16Cutilize the reflector cup 4 illustrated in FIGS. 5A-5B and multiplecuring operations similar to those previously described. As shown inFIG. 16A, a first quantity 14 of encapsulant material is deposited inthe reflective cavity 15 of the package 10. In some embodiments of thepresent invention, the first quantity 14 may be dispensed using aseparate (wetting) pre-dispense followed by another dispense. Withproper control of the amount of encapsulant material dispensed, surfacetension will cause the liquid encapsulant material 14 to cling to thelip 22, forming a meniscus as illustrated in FIG. 16A at a heightindicated at 14A. The initial meniscus formed by encapsulant material 14may be concave, convex or substantially flat as illustrated in FIG. 16A.

The dispensed encapsulant material 14 is cured, for example, by heating,and may shrink down to a lower height indicated at 14B. In theillustrated embodiment, the cured encapsulant material 14 shrinks downto form a concave surface 14C, which in three dimensions may besubstantially bowl-shaped (i.e. lowest in the center and slopingradially upwards). In some embodiments (in particular embodiments inwhich the first encapsulant material 14 is dispensed to form a concavesurface prior to curing), the encapsulant material 14 may be pre-cured,i.e. exposed to a lower temperature or for shorter cure times, such thatthe encapsulant material does not completely solidify but rather merelyforms a solid “skin” over its surface. The purpose of forming the skinis to prevent subsequently dispensed encapsulant material fromintermixing with the first encapsulant material 14. Subsequentencapsulant dispenses may contain wavelength conversion materials (suchas phosphors) and, as discussed above, it may be desirable for thephosphor-loaded luminescent conversion region to retain a characteristicshape rather than becoming intermixed with the first encapsulantmaterial 14. Subjecting the first encapsulant layer 14 to a pre-cureinstead of a full cure may speed the manufacturing process and mayresult in an improved interface between the first encapsulant materialand subsequent encapsulant regions.

As shown in FIG. 16B, a second quantity 16 of encapsulant material isthen dispensed into the cavity 15 onto bowl-shaped surface 14C. Thesecond encapsulant material 16 includes a luminescent wavelengthconversion material, such as a phosphor, in the illustrated embodiments.In some embodiments, the first encapsulant material 14 includes noluminescent wavelength conversion material. In other embodiments, thefirst encapsulant material 14 includes a lower concentration ofluminescent wavelength conversion material than the second encapsulantmaterial 16.

In some embodiments, as illustrated in FIG. 16B, the second encapsulantmaterial 16 may also cling to the same edge of the lip 22 to form aconvex meniscus. The second encapsulant material 16 is then cured (alongwith the first encapsulant material 14 if the first encapsulant material14 was only pre-cured before the second encapsulant material 16 wasdispensed). In some embodiments, the second encapsulant material 16 mayalso be pre-cured, i.e. exposed to a lower temperature or for shortercure times, in order to prevent or reduce the risk of subsequentlydispensed encapsulant material from intermixing with the secondencapsulant material 16. However, in other embodiments, the secondencapsulant material 16 may be more fully cured in order to solidify thematerial before the lens 20 is inserted into the cavity 15. As discussedbelow, once solidified, the second encapsulant material 16 may act as amechanical stop to assist with correct placement of the lens 20.

The resulting cured (or pre-cured) second encapsulant material 16defines a luminescent conversion element 19 characterized by anon-uniform thickness that is greatest near the center of the opticalcavity and that decreases radially towards the outer edge of theluminescent conversion element 19. In the illustrated embodiment, theluminescent conversion element 19 is a bi-convex structure including aconvex upper surface 19A and a convex lower surface 19B.

As mentioned above, while it is possible to form the luminescentconversion element 19 using the meniscus control methods describedherein, in other embodiments, the luminescent conversion element 19 maybe a pre-formed phosphor-loaded insert that is placed within thereflective cavity 15 of the package 10. Such a structure may have someadvantages for device performance and manufacturability. In particular,forming the luminescent conversion element 19 as a pre-formed insert mayresult in improved quality control as the pre-formed inserts may beindividually tested before insertion. In addition, by forming thephosphor-loaded luminescent conversion element 19 as a pre-formedinsert, liquid phosphor-loaded material does not have to be used in thefinal assembly process. This can provide benefits, as phosphor-loadedmaterial can be abrasive and can interfere with the operation ofautomated machinery. Finally, a cure step may be avoided by forming thephosphor-loaded luminescent conversion element 19 as a pre-formedinsert.

In further embodiments, a transparent, convex hemispherical mold (notshown) may be placed over first encapsulant 14 before or after it iscured in order to receive the second encapsulant 16. Upon curing, thesecond encapsulant 16 will take the shape of the convex hemisphericalmold, which may provide improved control over the final shape of theluminescent conversion element 19.

After formation or insertion of the luminescent conversion element 19, aquantity of a third encapsulant material 17 is dispensed within thecavity 15 as further illustrated in FIG. 16B. The third encapsulantmaterial 17 may be an optically transparent material, such as siliconeor epoxy, with no luminescent conversion material or a low concentrationof luminescent conversion material. Because the third encapsulantmaterial 17 is dispensed following a cure or pre-cure step, the phosphorconversion material embedded in luminescent conversion element 19 maynot substantially intermix with the third encapsulant material 17.

In some embodiments, as illustrated in FIG. 16B, the lip 22 may have aninner and outer edge thereon and the third quantity 17 of encapsulantmaterial may cling to the outer edge of the lip 22, forming a convexmeniscus above luminescent conversion element 19. Thus, the thirdencapsulant material 17 may also not contact or wick up the uppersidewall 5 to form a concave meniscus.

Referring to FIG. 16C, the lens 20 is inserted into reflective cavity 15and brought into contact with the uncured liquid third encapsulantmaterial 17. As such, the third encapsulant material 17 may be squeezedout from underneath the lens 20. However, in some embodiments of thepresent invention, instead of squeezing out onto the exposed uppersurfaces of the reflector cup and the lens (as shown in FIG. 2), theexcess of the third encapsulant material 17 is squeezed into andreceived by the moat 18, thus limiting wicking of the encapsulantmaterial 17 up the sidewall 5 even after the lens 20 is inserted and theconvex meniscus of third encapsulant material 17 shown in FIG. 16B isdisplaced. The encapsulant material 17 is then cured to attach the lens20 in the package 10 and to solidify the encapsulant material 17.

In some embodiments, the lens 20 is advanced into the reflective cavity15 until it contacts the luminescent conversion element 19 to establisha desired position for the lens 20 in the reflective cavity 15. In otherwords, the luminescent conversion element 19 may act as a mechanicalstop to assure correct placement of the lens 20. In other embodiments,the lens 20 is advanced into the reflective cavity 15 until it contactsa lip formed in the cavity sufficient to establish a desired positionfor the lens 20 in the reflective cavity 15, as illustrated in FIG. 10C.

In some embodiments, the first encapsulant material 14 may include ascattering material embedded therein for scattering light passingtherethrough, which may better improve angular uniformity of lightemission.

In some embodiments, the first encapsulant material 14 may have a highindex of refraction for better light extraction from the device 103. Ifluminescent conversion element 19 has a different index of refractionfrom that of the first encapsulant material 14, light rays passingthrough the interface between the two regions may be refracted, alteringthe light emission patterns of the device. If the index of refraction ofthe luminescent conversion element 19 is lower than that of firstencapsulant material 14, light rays will tend to be refracted away fromthe normal direction, which may result in a more pronounced path lengthdifference. The shape of luminescent conversion element 19 may be chosenor altered to offset such effects. For example, as discussed above, theluminescent conversion element 19 may be bi-convex, plano-convex orconcavo-convex.

An example of forming a plano-convex luminescent conversion elementusing meniscus control techniques described herein is illustrated inFIGS. 17A-17C. As shown therein, a quantity of first encapsulantmaterial 14 is deposited in the reflective cavity 15 of the package 10.With proper control of the amount of encapsulant material dispensed,surface tension will cause the liquid encapsulant material 14 to clingto the lip 22, forming a convex meniscus as illustrated in FIG. 17A at aheight indicated at 14A. After curing, the first encapsulant material 14relaxes to a height indicated at 14B, forming an approximately flatsurface 14C. Second encapsulant material 16 is then dispensed, forming aconvex meniscus that clings to an inner or outer edge of lip 22. Aftercuring, the second encapsulant material 16 forms a plano-convexluminescent conversion element 19 having a convex surface 19A above aplanar surface 19B. The remaining manufacturing steps are generally thesame as were described above in connection with FIGS. 16A-16C.

Using similar techniques, the luminescent conversion element 19 may beformed as a plano-convex region with a planar region above a convexsurface (FIG. 18A), a concavo-convex region with a convex surface abovea concave surface (FIG. 18B) or a concavo-convex region with a concavesurface above a convex surface (FIG. 18C). As discussed above, in eachembodiment, the luminescent conversion element 19 includes a wavelengthconversion material, such as a phosphor material. The first encapsulantmaterial 14 and the third encapsulant material 17 may have no wavelengthconversion material or a lower concentration of wavelength conversionmaterial compared to the luminescent conversion element 19. Although theembodiments of FIGS. 16A-C, 17A-C and 18A-C are illustrated inconnection with a reflector cup 4 as illustrated in FIGS. 5A-B, thetechniques described above are applicable to other reflector cupdesigns, including reflector cups that include multiple moats andreflector cups that do not include a moat.

Embodiments of methods of packaging a semiconductor light emittingdevice 103 in a reflector 4 having a lower 6 and an upper 5 sidewalldefining a reflective cavity 15 and incorporating a phosphor-loadedluminescent conversion element 19 with a non-uniform thickness will nowbe further described with reference to FIG. 19. As shown in theembodiments of FIG. 19, operations begin at Block 1900 by dispensing afirst quantity 14 of encapsulant material into the reflective cavity 15to form a first meniscus. The meniscus may have a convex, concave orsubstantially planar shape depending on the desired final shape of theluminescent conversion element 19. The shape of the meniscus isdetermined by the physical dimensions of the reflector 4 and thequantity of encapsulant dispensed into the cavity. The first quantity 14of encapsulant material is then cured or pre-cured (Block 1910). Next,Branch A of the flowchart of FIG. 19 may be followed if it is desired toform the luminescent conversion element 19 using meniscus controlmethods. Branch B may be followed if it is desired to form luminescentconversion element 19 using a pre-formed insert.

Following Branch A, a second quantity 16 of encapsulant materialcontaining a concentration of wavelength conversion material that isgreater than that of first encapsulant material 14 is dispensed onto thecured first encapsulant material 14 (Block 1920).

The second encapsulant material 16 is then cured or pre-cured to form aluminescent conversion element 19 (Block 1930).

If Path B is followed, then a pre-fanned luminescent conversion element19 is inserted into the cavity 15 in contact with first encapsulantmaterial 14 (Block 1950). In some embodiments, the step of curing thefirst quantity of encapsulant material may be performed after insertionof the pre-formed luminescent conversion element 19.

After formation or insertion of luminescent conversion element 19 (Block1930 or Block 1950), third encapsulant material 17 is dispensed withincavity 15 (Block 1960). In some embodiments of the present inventionincluding a lens, the lens 20 is positioned in the reflective cavity 15proximate the dispensed third quantity 17 of encapsulant material (Block1970). Positioning the lens 20 may include collapsing a meniscus ofthird encapsulant material 17 and moving a portion of the third quantity17 of encapsulant material into a moat 18, 24 with the lens 20 asillustrated in FIGS. 9C, 10C, 16C and 17C. In addition, as illustratedin FIG. 10C, the package may include a second lip 26′ having a heightgreater than that of the first lip 22. The height of the second lip 26′may be selected to provide a desired position for the lens 20 and thelens 20 may be moved into the reflective cavity 15 until it contacts thesecond lip 26′. In other embodiments of the present invention, asillustrated in FIGS. 9C, 16C and 17C, the lens 20 is advanced into thereflective cavity 15 until it contacts the luminescent conversionelement 19 sufficient to establish a desired position for the lens 20 inthe reflective cavity 15. The dispensed third quantity 17 of encapsulantmaterial is cured to attach the lens 20 in the reflective cavity 15(Block 1980).

The flowchart of FIG. 19 and the schematic illustrations of FIGS.16A-16C, 17A-17C and 18A-18C illustrate the functionality and operationof possible implementations of methods for packaging a light emittingdevice according to some embodiments of the present invention. It shouldbe noted that, in some alternative implementations, the acts noted indescribing the figures may occur out of the order noted in the figures.For example, two blocks/operations shown in succession may, in fact, beexecuted substantially concurrently, or may be executed in the reverseorder, depending upon the functionality involved.

Emission patterns for light emitting device packages will now be furtherdiscussed with reference to FIGS. 20A, 20B and 21. FIG. 20A is a polarplot of color-temperature for a glob-top light emitting diode (LED)emission pattern without a luminescent conversion element of the presentinvention generated using a goniometer. FIG. 20B is a polar plot ofcolor-temperature for a light emitting diode (LED) emission pattern witha luminescent conversion element according to some embodiments of thepresent invention. A comparison of FIG. 20B to FIG. 20A shows animprovement in uniformity provided by the luminescent conversion region(i.e., the radius of the emission pattern is more uniform in FIG. 20B).As seen in FIG. 20B, the packaged semiconductor light emitting devicehas a minimum color temperature (5.3 kK at about −85° approximately 26percent below a maximum color temperature (7.2 kK at about 0° thereofover the measured 180 (+/−90 from normal or central axis)-degree rangeof emission angles. Various embodiments of the present invention mayprovide a minimum color temperature no more than 30 percent below amaximum color temperature for the semiconductor light emitting devicepackage over a measured 180 (+/−90 from normal or central axis)-degreerange of emission angles or over a measured 120 (+/−45 from normal orcentral axis)-degree range of emission angles.

FIGS. 21A and 21B and 22A and 22B further illustrate improvement incolor uniformity obtained according to some embodiments of the presentinvention. FIGS. 21A and 21B are digitally analyzed plots of the nearfield emission pattern of a first packaged device including asubstrate/reflector assembly in which a Model C460XB900 light emittingdiode manufactured by Cree, Inc. was mounted. 0.0030 cc Silicone(example: vendor e.g. Nye Synthetic Lubricants) mixed with 4% YAG dopedwith Ce Phosphor (example: from Philips) was pre-dispensed over thelight emitting device, followed by a dispense of 0.0070 cc of the sameencapsulant. Next, the dispensed encapsulant was cured for 60 minutes ata temperature of 70 C. A second quantity of 0.0050 cc of clearencapsulant material was then dispensed into the optical cavity and alens was positioned in the optical cavity in contact with the secondquantity of encapsulant. The second quantity of encapsulant was thencured for 60 minutes at a temperature of 70 C. The resulting structurewas then energized and the near field emission pattern was recorded andanalyzed. The emission pattern shows a total CCT variation ofapproximately 2000 K over the measured 180 (+/−90 from normal or centralaxis)-degree range of emission angles.

FIGS. 22A and 22B are digitally analyzed plots of the near fieldemission pattern of a second packaged device including asubstrate/reflector assembly in which a C460XB900 light emitting diodemanufactured by Cree, Inc. was mounted. 0.0020 cc of clear silicone(example: vendor e.g. Nye Synthetic Lubricants) was pre-dispensed overthe light emitting device, followed by a first dispense of 0.0035 cc ofthe same encapsulant. The first encapsulant (including the pre-dispensedencapsulant) contained no wavelength conversion material. Next, thefirst encapsulant was cured for 60 minutes at a temperature of 70 C. toform a concave meniscus. A second quantity of 0.0045 cc encapsulantmaterial containing a wavelength conversion phosphor, namely 7% byweight of YAG doped with Ce Phosphor (example: from Philips) was thendispensed into concave meniscus formed by the first encapsulant. Thesecond encapsulant was then cured for 60 minutes at a temperature of 70C. to form a luminescent conversion element having a thickness that wasgreatest at the center of the optical cavity and that decreased radiallyoutward. A third quantity of 0.0050 cc encapsulant (which did notcontain any wavelength conversion material) was then dispensed into theoptical cavity and a lens was positioned in the optical cavity incontact with the third quantity of encapsulant. The third quantity ofencapsulant was then cured for 60 minutes at a temperature of 70 C. Theresulting structure was then energized and the near field emissionpattern was recorded and analyzed. The emission pattern shows a totalCCT variation of approximately 500 K over the same range of emissionangles.

In some embodiments of the present invention, a CCT variation of lessthan about 1000 K is provided over a measured 180, 120 or 90 (centeredon normal or central axis)-degree range of emission angles. In otherembodiments of the present invention, a CCT variation of less than about2000 K is provided over a measured 180, 120 or 90 (centered on normal orcentral axis)-degree range of emission angles. In yet furtherembodiments of the present invention, a CCT variation of less than about500 K is provided over a measured 120 or 90 (centered on normal orcentral axis)-degree range of emission angles. It will be understoodthat the CCT variation referred to herein is based on a primary emissionpattern of a device including primary optics processed with the devicewithout the use of any additional secondary optics added to or used incombination with the packaged semiconductor light emitting device toimprove color variation. Primary optics refers to the optics integral tothe device, such as a luminescent conversion element in combination witha lens built into the device as described for various embodiments of thepresent invention herein.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. Therefore, it is to be understood that the foregoing isillustrative of the present invention and is not to be construed aslimited to the specific embodiments disclosed, and that modifications tothe disclosed embodiments, as well as other embodiments, are intended tobe included within the scope of the appended claims. The invention isdefined by the following claims, with equivalents of the claims to beincluded therein.

1. A method of producing a semiconductor light emitting device,comprising: dispensing a first quantity of encapsulant material onto thelight emitting device; treating the first quantity of encapsulantmaterial on the light emitting device to form a hardened upper surfacethereof having a shape; and providing an optically transmissive elementon the upper surface of the treated first quantity of encapsulantmaterial, the optically transmissive element having a lower surfaceshape that substantially conforms to the upper surface of the treatedencapsulant material, wherein at least one of the first quantity ofencapsulant material or the optically transmissive element include awavelength conversion material.
 2. The method of claim 1, whereinproviding the optically transmissive element comprises: dispensing asecond quantity of encapsulant material on the upper surface of thetreated first quantity of encapsulant material; and curing the secondquantity of encapsulant material to define the optically transmissiveelement.
 3. The method of claim 2 wherein the optically transmissiveelement has a biconvex shape and wherein the shape is concave andwherein dispensing and curing the second quantity of encapsulantmaterial comprise dispensing and curing the second quantity ofencapsulant material to form a convex upper surface of the secondquantity of encapsulant material.
 4. The method of claim 2 wherein theoptically transmissive element has a plano-convex shape and wherein theshape is concave and wherein dispensing and curing the second quantityof encapsulant material comprise dispensing and curing the secondquantity of encapsulant material to form a planar upper surface of thesecond quantity of encapsulant material.
 5. The method of claim 2wherein the optically transmissive element has a plano-convex shape andwherein the shape is planar and wherein dispensing and curing the secondquantity of encapsulant material comprise dispensing and curing thesecond quantity of encapsulant material to form a convex upper surfaceof the second quantity of encapsulant material.
 6. The method of claim 2wherein the optically transmissive element has a concavo-convex shapeand wherein the shape is convex and wherein dispensing and curing thesecond quantity of encapsulant material comprise dispensing and curingthe second quantity of encapsulant material to form a convex uppersurface of the second quantity of encapsulant material.
 7. The method ofclaim 2 wherein the optically transmissive element has a concavo-convexshape and wherein the shape is concave and wherein dispensing and curingthe second quantity of encapsulant material comprise dispensing andcuring the second quantity of encapsulant material to form a concaveupper surface of the second quantity of encapsulant material.
 8. Themethod of claim 2 wherein treating the first quantity of encapsulantmaterial comprises pre-curing the first quantity of encapsulant materialto form a hardened skin on the upper surface thereof and wherein themethod further comprises curing the first quantity of encapsulantmaterial after providing the optically transmissive element.
 9. Themethod of claim 1 wherein the optically transmissive element comprises apre-formed insert and wherein providing the optically transmissiveelement on the upper surface comprises placing the pre-formed insert onthe upper surface of the treated first quantity of encapsulant material.10. A method of producing a semiconductor light emitting device,comprising: dispensing a first quantity of encapsulant material onto thelight emitting device; treating the first quantity of encapsulantmaterial on the light emitting device to form a hardened upper surfacethereof having a shape; and providing an optically transmissive elementon the upper surface of the treated first quantity of encapsulantmaterial, the optically transmissive element having a thickness at amiddle region of the light emitting device greater than at a regiondisplaced from the middle region of the light emitting device, whereinat least one of the first quantity of the encapsulant material or theoptically transmissive element include a wavelength conversion material.11. The method of claim 10, wherein providing the optically transmissiveelement comprises: dispensing a second quantity of encapsulant materialon the upper surface of the treated first quantity of encapsulantmaterial; and curing the second quantity of encapsulant material todefine the optically transmissive element.
 12. The method of claim 11,wherein treating the first quantity of encapsulant material comprisespre-curing the first quantity of encapsulant material to form a hardenedskin on the upper surface thereof and wherein the method furthercomprises curing the first quantity of encapsulant material afterproviding the optically transmissive element.
 13. The method of claim10, wherein the thickness of the optically transmissive elementcontinuously decreases as the optically transmissive element extendsradially outward from the middle region to the sidewall.
 14. The methodof claim 10, wherein the thickness of the optically transmissive elementvaries by more than ten percent of a maximum thickness of the opticallytransmissive element.
 15. The method of claim 10, wherein the opticallytransmissive element has a biconvex, plano-convex or concavo-convexshape.
 16. The method of claim 10, further comprising: dispensing asecond quantity of encapsulant material onto the optically transmissiveelement to form a convex meniscus of encapsulant material providing adesired shape of a lens; and curing the second quantity of encapsulantmaterial to form the lens for the packaged light emitting device fromthe encapsulant material.
 17. The method of claim 10, furthercomprising: dispensing a second quantity of encapsulant material ontothe optically transmissive element; positioning a lens on the dispensedsecond quantity of encapsulant material; and curing the dispensed secondquantity of encapsulant material to attach the lens.
 18. The method ofclaim 10, wherein the optically transmissive element comprises apre-formed insert and wherein providing the optically transmissiveelement on the upper surface comprises placing the pre-formed insert onthe upper surface of the treated first quantity of encapsulant material.19. A semiconductor light emitting device, comprising: a light emittingdevice; a first quantity of cured encapsulant material on the lightemitting device; and an optically transmissive element on an uppersurface of the first quantity of encapsulant material; and wherein atleast on of the first quantity of cured encapsulant material or theoptically transmissive element include a wavelength conversion materialand wherein the semiconductor light emitting device exhibits a variationof correlated color temperature across a 180 (+/−90 from centralaxis)-degree range of emission angles of less than 2000 K.
 20. Thedevice of claim 19, wherein the optically transmissive element has athickness at a middle region of the light emitting device greater thanat a region displaced from the middle region of the light emittingdevice.